Apparatus for straightening wire



Ailg. 15, 1967 H. A. FILLING I 3,335,764

7 APPARATUS FOR STRAIGH'IENING WIRE Filed May 19, 1965 INVENTOR.

/ 6 HUGH /'7. PILL/N6 wznwp United States Patent 3,335,764 APPARATUS FOR STRAIGHTENING WIRE Hugh A. Pilling, 982 N. th St., Kalamazoo, Mich. 49001 Filed May 19, 1965, Ser. No. 456,967 3 Claims. (Cl. 140-147) This invention relates to apparatus for straightening wire, particularly to an improved form of wire straightening die assemblage and to wire straightening apparatus employing the assemblage.

When articles are made from wire or from relatively small metal rods, it is usually essential that the Wire or rod be straightened before the article is formed. Wire, in particular, is generally shipped in the form of coils in which the wire is continuously bent on a radius which depends upon the size and diameter of the coil. Wire also often becomes kinked to a greater or lesser extent during handling and it is necessary that the straightening mechanism employed be adapted to remove all such distortions and deliver the wire to the forming apparatus in as nearly a straight condition as possible. At the same time, it is essential that as little marring of the surface of the Wire as possible be caused by the straightening apparatus.

Generally, the straightening of wire is effected by drawing the wire through a series of short, tubelike members, elg. through from 3 to 5 such members, often referred to as wire straightening dies or die elements, which have a die bore or port a little larger in diameter than the diameter of the wire and which are located with their longitudinal axes generally parallel with one another but displaced laterally, or offset, with respect to one another by 'a suitable distance. The dies are often mounted in a suitable framework or carriage, often referred to as an arbor, which rotates around the wire on an axis parallel with the general direction of travel of the wire, the carriage having a suitable passageway through it through which the wire travels through the successive die ports. The wire is thus required to follow a rotating sinuous or serpentine path through the series of dies during which time it is flexed in essentially all directions. When a bent or kinked section of the wire passes through the series of dies, it is flexed in a direction to correct the bend or kink by an amount which exceeds the elastic limit of the wire and the bend or kink is thusvremoved and the Wire straightened. Rods of relatively small diameter can be straightened in the same way. In practice, one or both ends of the bore in each die is flared and the curvature of the surface of the bore is formed to a carefully predetermined configuration to avoid any possibility of the wire sliding over any shoulder or discontinuity in the surface of the bore which would mar the smooth surface of the wire.

Numerous devices have been proposed and used widely for straightening wire employing the foregoing principle. In one conventional arrangement, the die carriage, or arbor, is in the form of an axially bored element through which extend a series of transverse bore which are usually angular in cross section. Each die assemblage is also angular in cross section and fits snugly in its respective transverse bore, being retained therein by suitablethreaded plugs engaging enlarged threaded ends of the transverse bore. By suitably adjusting the locations of the plugs in the ends of each bore, the respective die assemblage can be located at a desired position longitudinally in the bore. Each die member is provided near its midpoint with a suitably contoured die bore through which the wire is drawn. The individual die members are, of course, located in the Way mentioned so that the longitudinal axes of the die bores are offset with respect to one another to a desired extent.

, In other suggested arrangements it has been proposed to mount the die elements in antifriction bearings associated 3,335,764 Patented Aug. 15, 1967 with the carriage so that they can rotate freely as the wire is drawn through them. In other arrangements, the die elements have been formed as small cylindrical elements with an axial die bore, each element being retained between opposed jaws associated with the die assemblage. In the main, however, all of the heretofore proposed arrangements suffer from certain Well known disadvantages.

Wire straightening dies are, for longest wear, made of very hard materials. One of the most satisfactory materials from which wire straightening die elements have been fabricated is tungsten carbide, the parts generally being made by powder metallurgy procedures involving sintering for the final hardening step. Such fabrication procedures are well known and need not be described here. Suffice it to say that the properties of tungsten carbide which, although extremely hard, is known to be relatively brittle, do not permit the satisfactory mounting of dies formed of this material in antifriction hearings or in clamping devices as is possible with hardened steel dies. Because of the essentially noncompressible nature, extreme hardness and brittle nature of tungsten carbide, it is diflicult, if not impossible, to mount dies made of this material by any means which depends upon their being held rigidly in place entirely by frictional engagement of a mounting means with the die surface which will avoid all risk of the die being displaced to even a slight extent under the stresses encountered during the operation of the wire straightening machine. Knurled jaws, for example, fail to bite into the surface of such a die enough to prevent longitudinal slippage of the die when a sharp kink in the wire is encountered.

For these and other reasons it has become the custom when using dies made of tungsten carbide to form the entire die assemble of tungsten carbide: and to retain it in a suitable transverse bore in the rotating die carriage of the apparatus by means of threaded plugs according to the procedure mentioned previously. In this way little or no compressive pressure need be exerted upon the ends of the assemblage to hold it rigidly in position in the transverse bore. However, since the entire assemblage must, following conventional procedures, be considerably wider than, and several times as long as, the diameter of the die bore, and since it must be made entirely of tungsten carbide, it is clear that the amount of costly carbide necessary to make the assemblage is excessive. The difficulty of making large pieces or complicated shapes to acare seldom used. It is clear that any means which would permit a reduction in the amount of tungsten carbide employed per die, or any means which would increase the amount of wire which could be straightened using a single die, would be of great value in conserving valuable tungsten carbide and in reducing the cost of straightening wire and the like.

According to the present invention, the foregoing difiiculties are overcome readily and economically in the way which will be described. According to the invention a die assemblage is formed comprising a die element and a die holder. The die holder is formed with an interior cavity and is of noncircular exterior configuration adapted to fit snugly into a correspondingly configured transverse bore of a die carriage. The carriage can be entirely conventional and provided with a longitudinal bore through which the wire travels and in which the die elements are located to cause the wire to follow a rotating sinuous path in conventional manner. Although the die holder and corresponding transverse port extending through the die carriage will be described as generally rectangular in configuration, it should be mentioned that other configurations can be employed where desirable or convenient to prevent the die holder from rotating in the transverse bore. Thus the exterior surface of the die holder can, if desired, be oval in nature. The die holder can be retained in a desired position longitudinally of the transverse bore by any desired means, conveniently by conventional threaded plugs engaging threaded ends of the bore.

The die element is formed of a suitably hard material, preferably of tungsten carbide, and is located in the cavity of the die holder. The die element is formed as a somewhat elongated square or rectangular bar having a suitable generally U-shaped groove formed longitudinally along each of two of its opposite sides. Each groove is contoured so as to form approximately one half of a conventional die bore, the wire which is being straightened sliding longitudinally along the groove to effect the straightening of the wire. A series of such die assemblages, usually five in number, are, of course, located in a series of transverse ports in the die carriage.

Each die element is mounted in the die holder so that the longitudinal axis of the groove extends in a plane generally parallel with the longitudinal axis of the longitudinal bore of the rotating die carriage. The die element is bored transversely near its center and is secured in the die holder by a suitable die support, or pivot, pin extending through the bore and through appropriate holes in opposite walls of the die holder. The die element is free to rotate through a small angle on the pivot pin. With the series of die assemblages, each comprising a die and die holder, each located in appropriate oifset relationship position in a transverse bore of the die carriage, and with a wire sliding over successive offset die elements, the Wire is straightened without difficulty and without marring its surface.

Certain advantages of the invention are apparent from the accompanying drawing wherein, in the interest of clarity, certain features are shown on a somewhat exaggerated scale and wherein:

FIGURE 1 is a schematic plan view, partially broken away and partially in section, of a conventional rotatable die carriage showing its relationship to a wire being straightened and illustrating one method of rotating the carriage;

FIGURE 2 is a partial sectional elevation taken along the line IIII of FIGURE 1;

FIGURE 3 is an end elevation of a die assemblage of FIGURE 2 illustrating certain features of the assemblage;

FIGURE 4 is a sectional elevation taken along the line IV-IV of FIGURE 3;

FIGURE 5 is an elevation taken along the line V-V of FIGURE 3; and

FIGURE 6 is a sectional elevation of a die element taken along the line VIVI of FIGURE 4.

Referring to FIGURE 1 there is shown a cylindrical die carriage or arbor 11 of conventional design having an axial longitudinal bore, into one end of which an unstraightened wire 18 travels and from the other end of which the wire emerges in straightened condition at 21. The carriage 11 in the modification illustrated is provided at one end with a driven pulley 15 and is driven by way of a belt 13 running on a drive pulley 16 mounted on a power driven shaft 14. A series of transverse carriage bores 34, usually five in number, extend transversely through the carriage as illustrated more particularly in FIGURE 2. In the modification shown each transverse bore is generally rectangular in nature but is grooved along each of its lateral sides with a section of the bore wall consisting of a segment 40 of a circle somewhat greater in diameter than the width of the bore. The ends of the segmental sections 40 of the wall of the bore 34 are threaded to receive threaded die adjusting plugs 23, the function of which will be apparent.

Referring to FIGURES 3, 4 and 5, there is shown a die assemblage adapted to fit snugly into one of the transverse bores 34. The assemblage comprises a generally rectangular die holder 35 provided with an internal cavity 29. The exterior configuration of the die carrier as shown in FIGURE 5 corresponds to the configuration of the transverse bore 34 in the die carriage, in this instance being generally rectangular in nature and provided along each of its opposite sides with segmental protuberances 41 corresponding to the segmental grooves 40 formed in the die carriage. U-shaped grooves 25 are formed in the end sections 31 of the die holder serving as entry and exit ports, respectively, through which the wire which is being straightened can enter into and emerge from the interior cavity of the die holder so as to contact the die element therein in the way which will be described.

The die element 26, shown in central cross section in FIGURE 6, is formed of a suitably hard material, preferably tungsten carbide, and is conveniently of generally square or rectangular somewhat elongated configuration. The die element 26 is somewhat shorter than the length of the interior cavity 29 and is preferably approximately as thick as the width of the cavity, allowance being made for some movement of the die element in the cavity without danger of its binding on the interior surfaces of the walls of the cavity.

The die element 26 is bored transversely at its center point to provide a die pivot pin bore 27 which accommodates a pivot pin 19 which extends through the bore 27 and is retained at its ends in suitable holes in opposite side walls of the die holder. This arrangement is shown clearly in FIGURE 4 from which it will be apparent that the die element 26 is free to rotate to a greater or lesser extent on the pin 19 in a plane which, as will be shown, is parallel with the general direction of travel of a wire through the die carriage.

The die element 26 has a die groove 28 formed in each of two of its opposite sides such that as the die element rotates around the pin 19 the longitudinal axes of thegrooves 28 remain in the same plane as the general plane of travel of a wire through the carriage. This can be expressed conveniently by stating that the die grooves are in the top and bottom surfaces of the die element 26.

The die groove 28 is formed so as to be approximately semicircular at its mid section and is enlarged or flared toward each of its ends in a configuration corresponding approximately to that of a longitudinal one half of a circular die bore in a conventional wire straightening die. It will be appreciated, as is well known, that the actual configuration of a conventional die bore is diflicult, if not impossible, to define mathematically since its cross sectional configuration varies in diameter from point to point along its length, each end of the bore being essentially bell-shaped. The same considerations apply to the die groove 28 and it will thus be apparent to those familiar with the art how the groove 28 should be contoured. Sufiice it to say that the groove 28 is flared at its ends and is free of shoulders which would mar the surface of a wire sliding in the groove. The surface of the groove is, of course, highly polished. The corners of the die element 26 adjacent to the ends of the die groove are usually rounded somewhat to facilitate a certain amount of rotation of the element around the pivot pin 19 without the corners engaging the end walls of the die holder.

The manner of assembling the die assemblage of FIG- URES 3, 4 and 5 in the die carriage of FIGURE 1 is shown clearly in FIGURE 2. Each die assemblage is inserted into its appropriate transverse groove 34 and secured in an appropriate position therein by means of a pair of die adjusting plugs 23. It will be noted that the several die assamblages are inserted in the transverse bores so that adjacent assemblages face in opposite directions. It will be noted, furthermore, that the assemblages are located in the -transverse bores to provide for the wire which is being straightened to follow a sinuous path through the die grooves 28 of the several die members 26. When this condition is fulfilled, it will be apparent that each die assemblage is located somewhat ofr' center with respect to the longitudinal axis of the die carriage bore 12. To provide for better balance of the entire apparatus during high speed rotation about the wire, it is convenient to insert properly formed spacer blocks 17 in each transverse bore 34 between the die assemblage and the appropriate adjusting plug 23 to improve the balance of the apparatus. I

In operation, a wire which is to be straightened is fed into one end of the die longitudinal carriage bore 12, through the U-shaped groove 25 in the adjacent end of the first die holder, then along the die groove 28 and out through the U-shaped groove in the other end of the die holder. In similar fashion the wire is fed through the remaining die holders and eventually out of the opposite end of the die carriage. The die carriage is then rotated rapidly around the wire and the wire is caused to travel longitudinally through it.

It will be seen that in threading the wire through anyone of the die assemblages, some difficulty might be experienced if the die element 26 were to become tipped by rotation around the pin 19 so that the end of the element blocked partially the U-shaped groove 25 through which the end of the wire enters into the die holder cavity 29. To eliminate this difliculty it is convenient to fix a pair of pins 22 and 24 at suitable locations in a side wall of the die holder so that they extend for a suitable distance transversely into, but not necessarily entirely through, the cavity 29. A coil spring 32 is then mounted on the pin 22, which thus serves as a spring pivot pin. The ends of the spring 32 are elongated so that one of them rests on the other pin 24 which thus serves as a spring rest pin. The other prolonged ends of the spring engages the side of the die member opposite the groove through which the wire is being threaded. By making the prolonged ends, or arms, of the spring of suitable length, the die element 26 is kept in a tipped position such that there is no change of its blocking the groove 25 through which the wire is being fed through the die assemblage. On the other hand, the tension of the spring 32 on the die member is so slight as to offer .no appreciable resistance to proper pivoting of the member on the pin 19 when wire is being drawn through the apparatus. The die member 26 is thus able to pivot freely on the pin 19 under tension exerted on it by a wire being drawn along the die groove to accommodate itself to the precise optimum position for exerting maximum straightening effect on the wire with essentially no marring of the surface of the wire. It is, of course, apparent that although the use of a coil spring 32 in the way described is convenient, its employment is not essential to the invention. Spring arrangements other than that illustrated can, of course, be employed to accomplish the same purpose.

It will be clear that only one of the die grooves 28 engages the wire at any one time. Should the surface of the die groove in use eventually become worn sufiiciently to cause marring of the surface of the wire, it is only necessary to remove the pivot pin, reverse the die member and replace the pin so that the other die groove is used. If desired, the die member can be formed with a die groove on only one of its sides although, in the interest of economy, it is preferable to provide oppositely located grooves as illustrated.

It is known that in using wire straightening apparatus, it is necessary to adjust the amount of offset of the dies when shifting from one size of wire to another or even from wire of one size and temper to wire of the same size but of a different temper. In the case of conventional non-pivoting dies this leads to undesirable results. With the use of relatively soft dies the degree of wear of the die is rapid, particularly until the die is worn in for the particular size of wire being straightened. When, later, it is attempted to straighten a larger wire, the shoulders formed during the wearing in process will mar the surface of the larger wire to an extent which cannot betolerated. Such a worn in die can frequently be used to straighten a smaller diameter wire, but this involves a new wearing in process and renders the die unfit for reuse with the original size of wire.

When exceptionally hard dies which exhibit little wear are used in conventional apparatus, essentially no wear- .ing in of the die surface occurs but, because of the variation in the path of travel of the wire with respect to the die when the amount of otfset of a fixed die is changed, it is possible to use a given die on only a very narrow range of wire sizes to avoid what amounts to a point contacting of the wire with the die rather than the required smooth sliding contact of the wire along a relatively long section of the surface. This necessitates the provision of a large number of sets of dies and the actual changing of the dies in the machine each time a change of more than a minimal amount in the diameter or temper of the wire being straightened is made.

With the pivotable dies of this invention, however, these difficulties are overcome. A single set of dies can be employed for the entire range of wire sizes and tempers up to the largest sizes which can be accommodated by the particular die groove and arbor involved. Because the die is free to pivot, it adjusts itself to a position best suited to bear in nonmarring relationship on the wire regardless of the amount of offset of one die with respect to an adjacent die. Furthermore, with a sufiiciently hard die, which suffers little wear, it is entirely feasible to shift from large to small wire and, later on, back to large wire without the least difiiculty. It thus becomes possible using the pivotable die of this invention to use the same dies for long periods of time on wire of widely dilfering sizes and tempers without any difiiculty whatsoever.

I claim:

1. A wire straightening die assemblage comprising a die holder of non-circular exterior configuration having an interior cavity and being adapted to fit snugly mto a transverse bore in a rotatable die carriage,

a die member mounted pivotally in the die holder cavity on a die pivot pin extending transversely through the cavity and engaging opposite side walls of the cavity,

a die groove formed longitudinally in a surface of the die member, the plane of pivoting of the die member on the die pivot pin causing the longitudinal axis of the die groove to pivot in the plane of the general direction of travel of a wire through the assemblage,

and a cut-away portion of each end of the die holder wall forming entry and exit ports, respectively, adapted to allow passage of the wire into, and its emergence from, the die holder cavity while sliding in the die groove.

2. An assemblage as claimed in claim 1 including spring means located in the die holder cavity adapted to exert tension on the die member sufiicient to 'keep the member tipped on the pivot pin when no wire extends through the cavity to prevent its end from blocking the entry port in the end wall of the die holder through which a wire can be inserted into the die holder cavity.

3. In wire straightening apparatus the combination including:

a die carriage adapted to be mounted rotatably and to rotate about its longitudinal axis;

a central longitudinal bore through the die carriage adapted to the travel thereth-rough by wire being straightened by the apparatus;

a transverse non-circular bore extending through the die carriage and intersecting the longitudinal bore;

a die holder of exterior configuration corresponding to the-configuration of the transverse bore adapted to fit snugly therein and having an interior cavity;

a die member mounted pivotally in the die holder cavity on a die pivot pin extending through the cavity in a direction transverse to the longitudinal axis of the longitudinal bore of the die carriage and engaging opposite side walls of the cavity;

a die groove formed longitudinally in a surface of the die member, the plane of pivoting of the die member on the die pivot pin causing the longitudinal axis of the die groove to pivot in the plane of the general direction of travel of a wire traveling through the die carriage bore;

and a cut-away portion of each end of the die holder wall forming entry and exit ports, respectively, adapted to allow passage of a wire into, and its emergence from, the die holder cavity while sliding longitudinally in the die groove.

References Cited UNITED STATES PATENTS 1,594,570 8/1926 Sleeper 72-79 3,029,845 4/1962 Egedal 140147 3,277,682 10/1966 Kaestner 140-147 RICHARD J. HERBST, Primary Examiner. 

1. A WIRE STRAIGHTENING DIE ASSEMBLAGE COMPRISING A DIE HOLDER OF NON-CIRCULAR EXTERIOR CONFIGURATION HAVING AN INTERIOR CAVITY AND BEING ADAPTED TO FIT SNUGLY INTO A TRANSVERSE BORE IN A ROTATABLE DIE CARRIAGE, A DIE MEMBER MOUNTED PIVOTALLY IN THE DIE HOLDER CAVITY ON A DIE PIVOT PIN EXTENDING TRANSVERSELY THROUGH THE CAVITY AND ENGAGING OPPOSITE SIDE WALLS OF THE CAVITY, A DIE GROOVE FORMED LONGITUDINALLY IN A SURFACE OF THE DIE MEMBER, THE PLANE OF PIVOTING OF THE DIE MEMBER ON THE DIE PIVOT PIN CAUSING THE LONGITUDINAL AXIS OF THE DIE GROOVE TO PIVOT IN THE PLANE OF THE GENERAL DIRECTION OF TRAVEL OF A WIRE THROUGH THE ASSEMBLAGE, AND A CUT-AWAY PORTION OF EACH OF THE DIE HOLDER WALL FORMING ENTRY AND EXIT PORTS, RESPECTIVELY, ADAPTED TO ALLOW PASSAGE OF THE WIRE INTO, AND ITS EMERGENCE FROM, THE DIE HOLDER CAVITY WHILE SLIDING IN THE DIE GROOVE. 